The present invention generally relates to expansion cards adapted for use in host computer systems, including personal computers and servers. More particularly, the invention relates to thermal management of integrated circuit (IC) chips on expansion cards and the use of an extension of a mounting bracket to absorb and dissipate heat generated by IC chips to the environment outside a computer enclosure.
Power consumption and thermal dissipation of IC chips used in computer systems, including but not limited to personal computers and servers, has reached a threshold where the off-loading of heat to the environment has become a significant challenge in the operation and maintenance of the system infrastructure. In most instances, thermal management involves passive heat transfer techniques that utilize a heat sink or active heat transfer techniques that utilize combinations of heat sinks and forced convection (for example, fans) to absorb heat from a surface of an IC chip and then dissipate the thermal load into the surrounding environment through another surface that is typically larger and faces away from the IC chip.
The dissipation of heat into the environment is generally determined by the temperature differential between the dissipation surface and the environment and the properties of the coolant, which in most cases is a fluid (liquids and/or gases). The ambient temperature inside a computer enclosure is typically substantially above that of the ambient atmosphere surrounding the enclosure. Consequently, the temperature differential between the IC chip/heat sink and the environment within the enclosure is less than the temperature differential between the IC chip/heat sink and the ambient atmosphere outside the enclosure. More or less elaborate ventilation systems installed in computer enclosures, such as exhaust fans, are generally part of the specifications of computer form factors. For example, part of the ATX specifications defines the airflow within a computer system. Other methods to improve cooling efficiency include direct exhaust designs of expansion cards, which typically require an increase in height to a dual slot form factor in order to accommodate the exhaust vents. In addition, specialized exhaust fan solutions have been available that occupy any vacant slot in the rear of the computer enclosure and are typically mounted directly adjacent to a heat source in order to maximize removal of hot air.
All solutions mentioned above have the drawback of increased cost and potential failure of moving parts. Therefore, a highly desirable solution would entail a more direct and passive conductance of thermal energy from a heat source within a computer enclosure to the ambient atmosphere outside the enclosure.